Glossary

A type of switch used in single-phase motors to disconnect the starting winding when the motor gets up to its rated speed.

Electrical measuring device that detects the amount of current flow imposed on the system without breaking the circuit based on the strength of the magnetic field created by the intensity of the current flow in the system

An assembly consisting of many turns of wire wound together with the purpose of creating an electric magnet strong enough to be used to open and close sets of contacts. Referred to as the “heart” of a contactor or motor starter.

Electromagnetically or electronically controlled device that controls all electrical loads except motors through a set of electrically operated physical contacts.

Common language of all control systems used to set foundational rules regarding the design and implementation of logic diagrams

Refers to the process of changing the crystalline structure of a semiconductor material by adding impurities to alter its conductive properties.

A rotating switch that manually reverses the order of the motor leads thereby reversing the direction of the motor rotation.

The flow of electrical current in an electrical circuit measured in amperes (A).

The resultant magnetic field produced any time electric current passes through a conductor.

The most widely accepted theory used by electricians that states current flows from negative to positive polarity.

Machine that uses electromagnetic induction to convert mechanical energy into electrical energy.

Negligible voltage induced into most electricals systems; although not considered dangerous, its presence or lack thereof is a great indicator of the quality of the electrical measuring device being used.

The property of matter by which a mass persists in its state of rest or motion until acted upon by an external force.

Specialized schematic drawings depicting two vertical rails and horizontal rungs used to convey the logic of a control system.

Electrical testing device that measures insulation integrity of electrical conductors after installation to ensure proper and safe operation usually before new building certification.

A device that converts electrical energy into rotational movement through the principle that current carrying conductor moving through a magnetic field will tend to be forced out of the field at right angles.

Specialized contactor that includes thermal overload protection intended to control and protect an electric motor.

National electrical manufacturing association developed to set the standards for all electrical devices in North America.

Ohm’s law states that current in a circuit is proportional to the voltage and inversely proportional to the resistance. Any unknown value can be determined when the other two values are known.

Thermal, magnetic, or electronically controlled component of a motor starter that protects the motor from damage caused by excessive heat.

Electrical testing device used to verify the direction of rotation of three-phase systems.

Also known as solar cells, are devices that turn sunlight into electricity using the photovoltaic effect.

(Programmable logic controller) Solid-state device that takes the place of more rudimentary motor starters and relays allowing for more seamless automation of control circuits.

Intentional reversal of a motor intended to facilitate the rapid stopping of motor rotation.

this ratio of true power to reactive power indicates the efficiency of any given electrical system and is directly related to a phase shift of voltage and current.

The manufacture’s terminal numbers that are used to identify and separate the different components included in a ladder diagram.

A electromechanical switch controlled by an electromagnet to operate a set of electrical contacts.

A base line indicator of the quality of a particular motor specifying how much excessive current the motor will tolerate for a short time.

A dangerous condition that occurs in three-phase systems where a single phase is lost, usually due to power outage, causing a harmful imbalance in the system.

Device comprised of an electric coil that changes the magnetic field created by electric current flow into linear mechanical movement.

An electrical device common to most AC electrical systems that steps up or down voltage and current through a primary and secondary coil using electromagnetic induction.

Crucial problem-solving skill involving the systematic elimination of the various parts of a system to isolate a problem.

Variable frequency drive used to control a motor through the use of a DC bus that alters the frequency and voltage applied to a motor.